1. Field of the Invention
This invention relates to an Fe-N soft magnetic thin film and more particularly, to an improvement in its heat resistance. The invention also relates to magnetic head using such a magnetic thin film as mentioned above.
2. Description of the Prior Art
In the field of magnetic recording, there is a great tendency toward high density recording or recording at short wavelengths, which requires magnetic recording mediums to have a high coercive force and a high residual magnetic flux density. On the other hand, materials for a magnetic head are required to have a high saturation magnetic flux density, a high magnetic permeability and a low coercive force in order to make the best use of the characteristics of the magnetic recording medium.
As one of soft magnetic materials which satisfy such requirements, there are hitherto known Fe-N materials. In fact, studies have been made to utilize, as a core of a magnetic head, the material as a thin film which is formed by a vapor phase plating technique such as sputtering.
However, the Fe-N-based soft magnetic thin film has the drawback that the thermal stability is poor. In the fabrication process of the magnetic head, it is essential to conduct a fusing step using high melting glass in order to ensure reliability. This step needs thermal treatment at high temperatures, so that the above drawback becomes serious.
Under these circumstances, studies have been continued with respect to an improvement of the thermal stability of the Fe-N-based soft magnetic thin film. For instance, the present applicant discloses in Japanese Laid-open Patent Application No. 63-299219 Fe-N-based soft magnetic thin films in which a small amount of a third element is incorporated to improve the thermal stability.
The melting point of glass used for fusion during the course of fabrication of a magnetic head should preferably be as high as possible for the purpose of ensuring the reliability. For instance, with a bulk-type magnetic head, a glass fusion step using approximately 550.degree. C. is usually adopted. Accordingly, where a soft magnetic thin film is applied as a core material, a glass fusion step at approximately 550.degree. C. is necessary. Materials for the thin film should have good soft magnetic characteristics and a high saturation magnetic flux density after the thermal treatment at such temperatures as indicated above.